Objective To investigate the role of wild-type XPD in SMMC-7721 hepatoma cells,its re-lationship with wild-type p53.CDK7 and c-myc.And the apoptosis mechanism of SMMC-7721 hepatoma cells.Methotis We inserted the human length XPD into the pEGFP-N2 plasmid vector which expresses the green fluorescence protein(GFP).And the pEGFP-N2 and pEGFP-N2-XPD were transfected into SMMC-7721 hepa-toma cell lines stably.Cel lines for omparison were matched on the sanle genetic background and passage.The expression of wild-type XPD,CDK7,p53,c-myc waft detected by RT-PCR,Westem blot.Cell growth wag detet-ed by MTT FCM wag employed for examining the cell cycle and apoptosis of the transfected SMMC-7721 hepa-toms cells.Results ①SMMC-7721-pEGFP-N2-xPD and SMMC-7721-pEGFP-N2 express the green fluores-cence protein which could be detected under the immunoffuorescence microscope.②RT-PCR The relative ex-\pression of p53 mRNA,XPD mRNA in the SMMC-7721,SMMC-7721-pEGFP-N2 and SMMC-7721-pEGFP-N2-XPD,the relative expression of p53 mRNA,XPD mRNA in the SMMC-7721-pEGFP-N2-XPD was signifiantly higher than other two oontrols(P<0.01).Othewise,the relative expression of CDK7 mRNA,c-myc mRNA Wag signifi-antlv lower than other two oontrols(P<0.01),the difference of two controls was not signifiant(P>0.05). ③Western blot The relative expression of p53,XPD protein was signifiantly higher than other two oontrols (P<0.01).Othewise,the relative expression of CDK7,c-Myc protein was signifiantly lower than other two oontrols(P0.05).④MTT The ressuh showedthat the proliferative ability of SMMC-7721-pEGFP-N2-XPD was much more descreaged than other two oontrols (P<0.05),the other two oontrols were not different(P>0.05).⑤FCM Wild-type XPD gene could change the cell8 and induce apoptitise in vitro though the result of FCM.Conclusions The pEGFP-N2 and pEGFP-N2-XPD were transfected into SMMC-7721hepatoma cell lines stably,wild-type XPD could decreaSe the expres-sion of CDK7,c-myc and increase the expression of p53.Wild-type.XPD could inhibit the activity of cell growth and change cell cycle,as well as induce cell apoptosis in SMMC-7721 hepatoma cell line in vitro.